Retinal ganglion cells comprise about 20 types, and for each type the dendritic arbors tile the plane of the retina completely and efficiently. We are investigating, using confocal microscopy, the degree to which arbors of different types intermingle in the inner plexiform layer, and quantitating this arborization. Confocal microscopy already has shown that some of our views of the 3D nature of these cells is incorrect, and needs to be reevaluated.